Fracture strength analysis of slurry cut mc-Si wafers

The fracture strength variation across the surface of multi-crystalline silicon (mc-Si) wafers cut by multi-wire slurry sawing (MWSS) was studied in this paper. As-sawn 156×156mm² mc-Si wafers were diced in two orthogonal orientations relative to the wire speed direction to yield small rectangular samples whose fracture strength was measured using the four line bending method. It is shown that the fracture strength of the wafer increases gradually from wire entry to wire exit along the wire speed direction whereas the variation in strength in the wire feed direction is small. Wafer samples bent in the orientation perpendicular to the wire speed direction show a slightly higher fracture strength than those bent parallel to the wire speed direction. Wafer samples from an interior and a corner brick show similar fracture strength variation. The results also reveal the critical role of abrasive-induced surface damage and the associated fracture strength of the silicon wafers.